13.16 Value RAM — Address 15h–3Fh

Address A6–A0

Description

15h

Manufacturers Test Register

19h

20h

+2.5Vin reading

21h

Vccp1 reading

22h

+3.3Vin reading

23h

+5Vin reading

24h

+12Vin reading

25h

Vccp2 reading

26h

Reserved reading

27h

Temperature reading (8 MSBs)

28h

FAN1 reading

Note: This location stores the number of counts of the internal clock per revolution.

29h

FAN2 reading

Note: This location stores the number of counts of the internal clock per revolution.

2Ah

Reserved

2Bh

+2.5Vin High Limit

2Ch

+2.5Vin Low Limit

2Dh

Vccp1 High Limit

2Eh

Vccp1 Low Limit

2Fh

+3.3Vin High Limit

30h

+3.3Vin Low Limit

31h

+5Vin High Limit

32h

+5Vin Low Limit

33h

+12Vin High Limit

34h

+12Vin Low Limit

35h

Vccp2 High Limit

36h

Vccp2 Low Limit

37h

T_CRIT Limit (Extended Mode)

38h

LOW Limit (Extended Mode)

39h

HIGH Temperature Limit

3Ah

HIHYST Temperature Limit

3Bh

FAN1 Fan Count Limit

Note: It is the number of counts of the internal clock for the Low Limit of the fan speed.

3Ch

FAN2 Fan Count Limit

Note: It is the number of counts of the internal clock for the Low Limit of the fan speed.

3Dh

Reserved

3Eh

Company Identification. The number in this register identifies National Semiconductor (0000 0001)

3Fh

Stepping Register LM81 revision number (0000 0011)

Note: Setting all ones to the high limits for voltages and fans (0111 1111 binary for temperature) means interrupts will never be generated except the case when volt-

ages go below the low limits.

For voltage input high limits, the device is doing a greater than comparison. For low limits, however, it is doing a less than or equal to comparison.

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